The search giant claims that the ad, first spotted in August, used Baidu’s office building as a backdrop for the text: “I heard my company’s culture has changed from simple and reliable [jian dan ke yi lai, 简单可依赖] to simple and shameless [jian dan ke yi lai, 简单可以赖],” changing one character to play on the company’s slogan.

The ad appeared to guide prospective new users to a Maimai user registration page, which included a download link to the Maimai app.

In China’s cutthroat online content and advertising industry, such a legal battle forms part of the intensified competition in the sector. Bytedance, now the world’s most valuable startup, is locked in a fierce rivalry with Baidu as well as social media giant Tencent. Maimai is known as being Linkedin’s biggest rival in China and is the country’s first professional networking unicorn. Baidu’s filing against Bytedance marks the latest in a series of spats between the two companies.

Baidu has accused Taou.com, Maimai’s operator, of defaming its reputation by promoting the ad. The search giant also said Jinri Toutiao should be held accountable for allowing ads on its platform that contain infringing content.

Baidu demands that the companies cease the infringement, pay RMB 5 million in compensation for the company’s losses, and apologize.

A Bytedance representative said the company could not comment on the matter as the case is ongoing.